President Donald Trump has issued new restrictions on people trying to enter the United States from eight nations -- adding North Korea and Venezuela to a list that also includes Iran -- to replace his expiring travel ban.

Trump signed a proclamation on September 24 implementing a range of restrictions that will apply to citizens of Chad, Iran, Libya, Somalia, Syria, Yemen, North Korea, and Venezuela.

Limitations on citizens of Sudan were lifted while Iraqi citizens face enhanced scrutiny, or vetting, but will not be subject to travel prohibitions.

The new restrictions will go into effect on October 18, eight days after the court is due to hear oral arguments over the legality of Trump's previous ban.

"Making America Safe is my number one priority. We will not admit those into our country we cannot safely vet," Trump said a tweet.

Iran's Foreign Minister Mohammed Javad Zarif criticized Trump's order earlier on September 25, writing on Twitter: "Trump's fake empathy for Iranians rings ever more hollow, with his new and even more offensive travel ban against such outstanding citizens."

Zarif issued the statement from New York, where he has been attending sessions of the United Nations General Assembly.

The measures restricting travel to the United States include an indefinite ban on visas for citizens of countries like Syria.

A suspension of nonimmigrant visas for citizens of Venezuela will apply only to certain government officials and their immediate families.

Venezuela and North Korea are the only two non-Muslim majority nations on the list.

The previous ban, which sparked international outrage and legal challenges when enacted in March, expired on September 24.

The new policy may complicate the Supreme Court's review of the expired ban, which is scheduled for argument next month.